Megaflo 250 DDD stoped working

[karloszh]

Hi all. I have a 250 litre Megaflo electric water heater at my company that has been installed about 9 year ago and it's been working perfectly. In this time we had 3 sets of heating elements replaced, the last set being installed in May this year. (it uses 3 heating elements)
Since last month I am not sure for what reason it stopped heating the water. I called one electrician who checked the elements and reseted them from the little reset button from behind the control panel behind each heating element, which brought it back to life and started working again, but only for 1 day. The second day it was not heating the water again. So i reseted the elements again and it came back to life and it's been doing the same ever since. I reset it every morning and then the second morning it's not working again.
Does anyone had the same issue, or has any idea of a solution that could fix the problem without replacing the complete unit?
I would appreciate any advice.

 

[ericmark]

I will guess the thermostat has failed and pressing button on the cut out will allow it to heat up until the safety cut out trips again, what you are doing is dangerous, as if the cut out fails water could boil. Likely thermostat needs changing.

 

[OvertonPlumber]

Normally the triple d cylinder was on a 3 phase supply as it has 3 immersions and can pull quite a bit of juice. They cost silly money when. New but can pretty much produce continuous hot water and are favoured by hairdressers salons.
The control Thermostats can be changed out quickly and most likely what the sparky did however eventually the entire immersion heater needs changing as they corro de and get covered in scale.
It's quite awkward to do the lower immersion on the newer Cylinders the shaped immersion as you need to keep the heater pushed in while you tighten the grab ring otherwise it's easy to pinch the rubber grommet. Top two are fine.
My company give me 2 hours to drain them down change over and refill. Pain in ass when it's 10th floor on towerblocks and van is 10 minute walk away..
Always drain it fully and replace the centre of the drainoff valve.